Hypothermia is a drop in body temperature to 95 degrees Fahrenheit (F) or less and can be fatal if not detected promptly and treated properly. The condition usually develops over a period of time, anywhere from a few days to several weeks. Even consistent, mildly cool indoor temperatures of 60 degrees to 65 degrees F can trigger hypothermia.

Infants lose body heat more quickly than adults, and the elderly often make less body heat because of a slower metabolism and less physical activity. IDPH recommends setting the thermostat above 65 degrees F and checking on elderly friends and neighbors frequently to ensure their homes are adequately heated.